Golf balls having a low modulus HNP layer and a high modulus HNP layer

ABSTRACT

The present invention is directed to golf balls consisting of a multi-layer core and a cover. The multi-layer core consists of a center and an outer core layer that are both soft relative to a hard intermediate core layer. The outer core layer is preferably thin relative to the center and the outer core layer. The multi-layer core includes at least one layer formed from a low modulus HNP composition and at least one layer formed from a high modulus HNP composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/946,024, filed Nov. 15, 2010, now U.S. Pat. No. 8,057,324, which is acontinuation of U.S. patent application Ser. No. 12/125,239, filed May22, 2008, now U.S. Pat. No. 7,833,112, which is a continuation-in-partof U.S. patent application Ser. No. 12/102,515, filed Apr. 14, 2008, nowU.S. Pat. No. 7,513,838, which is a continuation of U.S. patentapplication Ser. No. 11/694,029, filed Mar. 30, 2007, now U.S. Pat. No.7,357,736, the entire disclosures of which are hereby incorporatedherein by reference. U.S. patent application Ser. No. 12/125,239 is alsoa continuation-in-part of U.S. patent application Ser. No. 11/972,240,filed Jan. 10, 2008, now U.S. Pat. No. 7,722,482, the entire disclosureof which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is directed to golf balls comprising a multi-layercore and a cover, wherein the core comprises a layer formed from a lowmodulus HNP composition and a layer formed from a high modulus HNPcomposition. The present invention is not limited by which core layer isformed from the low modulus HNP composition and which core layer isformed from the high modulus HNP composition, so long as both layers arepresent in the core of the golf ball.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solidand wound. Solid golf balls include one-piece, two-piece (i.e., singlelayer core and single layer cover), and multi-layer (i.e., solid core ofone or more layers and/or a cover of one or more layers) golf balls.Wound golf balls typically include a solid, hollow, or fluid-filledcenter, surrounded by a tensioned elastomeric material, and a cover.

Golf ball core and cover layers are typically constructed with polymercompositions including, for example, polybutadiene rubber,polyurethanes, polyamides, ionomers, and blends thereof. Ionomers,particularly ethylene-based ionomers, are a preferred group of polymersfor golf ball layers because of their toughness, durability, and widerange of hardness values.

Golf ball compositions comprising highly neutralized acid polymers areknown. For example, U.S. Patent Application Publication No.2003/0130434, the entire disclosure of which is hereby incorporatedherein by reference, discloses melt-processible, highly-neutralizedethylene acid copolymers and process for making them by incorporating analiphatic, mono-functional organic acid in the acid copolymer and thenneutralizing greater than 90% of all the acid groups present. The use ofsuch compositions in various golf ball layers is disclosed. Also, U.S.Patent Application Publication No. 2005/0148725, the entire disclosureof which is hereby incorporated herein by reference, discloses ahighly-resilient thermoplastic composition comprising (a) an acidcopolymer, (b) a salt of a high molecular weight, monomeric organicacid; (c) a thermoplastic resin; (d) a cation source; and (e)optionally, a filler. The reference also discloses one-piece, two-piece,three-piece, and multi-layered golf balls comprising thehighly-resilient thermoplastic composition.

While various uses for highly neutralized acid polymers in golf ballshave been discovered, there is a need in the industry to broaden theapplicability of highly neutralized acid polymers to particular golfball constructions having desirable spin, feel, and COR properties. Thepresent invention provides such golf ball constructions through the useof a layer formed from a low modulus HNP composition and a layer formedfrom a high modulus HNP composition.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is directed to a golf ballcomprising a core and a cover. The core has an overall diameter of from1.40 inches to 1.60 inches and consists of a center having a diameter offrom 0.50 inches to 1.50 inches and a center hardness (H) of from 20Shore C to 70 Shore C, an intermediate core layer having a surfacehardness (I) of 40 Shore C or greater, and an outer core layer having asurface hardness (S) of from 20 Shore C to 70 Shore C, and H<I and S<I.The intermediate core layer is formed from a high modulus HNPcomposition comprising a highly neutralized ethylene/(meth)acrylic acidcopolymer having a modulus of from 25,000 psi to 150,000 psi. The outercore layer is formed from a low modulus HNP composition comprising ahighly neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylatecopolymer having a modulus of from 1,000 psi to 50,000 psi. The modulusof the highly neutralized copolymer of the low modulus HNP compositionis at least 10% less than the modulus of the highly neutralizedcopolymer of the high modulus HNP composition.

In another embodiment, the present invention is directed to a golf ballcomprising a core and a cover. The core has an overall diameter of from1.40 inches to 1.60 inches and consists of a center having a diameter offrom 0.50 inches to 1.50 inches and a center hardness (H) of from 20Shore C to 70 Shore C, an intermediate core layer having a surfacehardness (I) of 40 Shore C or greater, and an outer core layer having asurface hardness (S) of from 20 Shore C to 70 Shore C, and H<I and S<I.The center is formed from a low modulus HNP composition comprising ahighly neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylatecopolymer having a modulus of from 1,000 psi to 50,000 psi. Theintermediate core layer is formed from a high modulus HNP compositioncomprising a highly neutralized ethylene/(meth)acrylic acid copolymerhaving a modulus of from 25,000 psi to 150,000 psi. The modulus of thehighly neutralized copolymer of the low modulus HNP composition is atleast 10% less than the modulus of the highly neutralized copolymer ofthe high modulus HNP composition.

In another embodiment, the present invention is directed to a golf ballcomprising a core and a cover. The core has an overall diameter of from1.40 inches to 1.60 inches and consists of a center having a diameter offrom 0.50 inches to 1.50 inches and a center hardness (H) of from 20Shore C to 70 Shore C, an intermediate core layer having a surfacehardness (I) of 40 Shore C or greater, and an outer core layer having asurface hardness (S) of from 20 Shore C to 70 Shore C, and H<I and S<I.The center is formed from a low modulus HNP composition comprising ahighly neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylatecopolymer having a modulus of from 1,000 psi to 50,000 psi. The outercore layer is formed from a high modulus HNP composition comprising ahighly neutralized ethylene/(meth)acrylic acid copolymer having amodulus of from 25,000 psi to 150,000 psi. The modulus of the highlyneutralized copolymer of the low modulus HNP composition is at least 10%less than the modulus of the highly neutralized copolymer of the highmodulus HNP composition.

In yet another embodiment, the present invention is directed to a golfball comprising a core and a cover. The core has an overall diameter offrom 1.40 inches to 1.60 inches and consists of a center having adiameter of from 0.50 inches to 1.50 inches and a center hardness (H) offrom 20 Shore C to 70 Shore C, an intermediate core layer having asurface hardness (I) of 40 Shore C or greater, and an outer core layerhaving a surface hardness (S) of from 20 Shore C to 70 Shore C, and H<Iand S<I. The center is formed from a high modulus HNP compositioncomprising a highly neutralized ethylene/(meth)acrylic acid copolymerhaving a modulus of from 25,000 psi to 150,000 psi. The outer core layeris formed from a low modulus HNP composition comprising a highlyneutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymerhaving a modulus of from 1,000 psi to 50,000 psi. The modulus of thehighly neutralized copolymer of the low modulus HNP composition is atleast 10% less than the modulus of the highly neutralized copolymer ofthe high modulus HNP composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a golf ball according to oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a golf ball 30 according to one embodiment of the presentinvention, including a center 32, an intermediate core layer 34, anouter core layer 36, and a cover 38. While shown in FIG. 1 as a singlelayer, cover 38 may be a single-, dual-, or multi-layer cover.

Golf balls of the present invention have at least two layers formed fromhighly neutralized acid polymer (“HNP”) compositions. More particularly,golf balls of the present invention have at least one layer formed froma low modulus HNP composition, and at least one layer formed from a highmodulus HNP composition.

As used herein, “highly neutralized acid polymer” refers to an acidpolymer after at least 80%, preferably at least 90%, more preferably atleast 95%, and even more preferably 100%, of the acid groups of the acidpolymer are neutralized.

As used herein, “modulus” refers to flexural modulus as measured using astandard flex bar according to ASTM D790-B.

For purposes of the present disclosure, material hardness is measuredaccording to ASTM D2240 and generally involves measuring the hardness ofa flat “slab” or “button” formed of the material. It should beunderstood that there is a fundamental difference between “materialhardness” and “hardness as measured directly on a golf ball.” Hardnessas measured directly on a golf ball (or other spherical surface)typically results in a different hardness value than material hardness.This difference in hardness values is due to several factors including,but not limited to, ball construction (i.e., core type, number of coreand/or cover layers, etc.), ball (or sphere) diameter, and the materialcomposition of adjacent layers. It should also be understood that thetwo measurement techniques are not linearly related and, therefore, onehardness value cannot easily be correlated to the other. Unless statedotherwise, the hardness values given herein for cover materials,including inner cover layer materials and outer cover layer materials,are material hardness values measured according to ASTM D2240, with allvalues reported following 10 days of aging at 50% relative humidity and23° C.

The surface hardness of a golf ball layer is obtained from the averageof a number of measurements taken from opposing hemispheres, taking careto avoid making measurements on the parting line of the core or onsurface defects, such as holes or protrusions. Hardness measurements aremade pursuant to ASTM D-2240 “Indentation Hardness of Rubber and Plasticby Means of a Durometer.” Because of the curved surface, care must betaken to insure that the golf ball or golf ball subassembly is centeredunder the durometer indentor before a surface hardness reading isobtained. A calibrated, digital durometer, capable of reading to 0.1hardness units is used for all hardness measurements and is set to takehardness readings at 1 second after the maximum reading is obtained. Thedigital durometer must be attached to, and its foot made parallel to,the base of an automatic stand, such that the weight on the durometerand attack rate conform to ASTM D-2240.

The center hardness of a core is obtained according to the followingprocedure. The core is gently pressed into a hemispherical holder havingan internal diameter approximately slightly smaller than the diameter ofthe core, such that the core is held in place in the hemisphericalportion of the holder while concurrently leaving the geometric centralplane of the core exposed. The core is secured in the holder byfriction, such that it will not move during the cutting and grindingsteps, but the friction is not so excessive that distortion of thenatural shape of the core would result. The core is secured such thatthe parting line of the core is roughly parallel to the top of theholder. The diameter of the core is measured 90 degrees to thisorientation prior to securing. A measurement is also made from thebottom of the holder to the top of the core to provide a reference pointfor future calculations. A rough cut, made slightly above the exposedgeometric center of the core using a band saw or other appropriatecutting tool, making sure that the core does not move in the holderduring this step. The remainder of the core, still in the holder, issecured to the base plate of a surface grinding machine. The exposed‘rough’ surface is ground to a smooth, flat surface, revealing thegeometric center of the core, which can be verified by measuring theheight of the bottom of the holder to the exposed surface of the core,making sure that exactly half of the original height of the core, asmeasured above, has been removed to within ±0.004 inches. Leaving thecore in the holder, the center of the core is found with a center squareand carefully marked and the hardness is measured at the center mark.

Golf ball cores of the present invention may have a zero or negative orpositive hardness gradient. A hardness gradient is defined by hardnessmeasurements made at the surface of the layer (e.g., center, outer corelayer, etc.) and radially inward towards the center of the ball,typically at 2 mm increments. For purposes of the present invention,“negative” and “positive” refer to the result of subtracting thehardness value at the innermost portion of the golf ball component fromthe hardness value at the outer surface of the component. For example,if the outer surface of a solid core has a lower hardness value than thecenter (i.e., the surface is softer than the center), the hardnessgradient will be deemed a “negative” gradient. In measuring the hardnessgradient of a core, the center hardness is first determined according tothe procedure above for obtaining the center hardness of a core. Oncethe center of the core is marked and the hardness thereof is determined,hardness measurements at any distance from the center of the core may bemeasured by drawing a line radially outward from the center mark, andmeasuring and marking the distance from the center, typically in 2 mmincrements. All hardness measurements performed on a plane passingthrough the geometric center are performed while the core is still inthe holder and without having disturbed its orientation, such that thetest surface is constantly parallel to the bottom of the holder. Thehardness difference from any predetermined location on the core iscalculated as the average surface hardness minus the hardness at theappropriate reference point, e.g., at the center of the core for asingle, solid core, such that a core surface softer than its center willhave a negative hardness gradient. Hardness gradients are disclosed morefully, for example, in U.S. patent application Ser. No. 11/832,163,filed on Aug. 1, 2007; U.S. patent application ser. No. 11/939,632,filed on Nov. 14, 2007; U.S. patent application Ser. No. 11/939,634,filed on Nov. 14, 2007; U.S. patent application Ser. No. 11/939,635,filed on Nov. 14, 2007; and U.S. patent application Ser. No. 11/939,637,filed on Nov. 14, 2007; the entire disclosure of each of thesereferences is hereby incorporated herein by reference.

Low Modulus HNP Composition

Low modulus HNP compositions of the present invention comprise at leastone low modulus HNP having a modulus within a range having a lower limitof 1,000 or 5,000 or 10,000 psi and an upper limit of 17,000 or 25,000or 28,000 or 30,000 or 35,000 or 45,000 or 50,000 or 55,000 psi. In apreferred embodiment, the modulus of the low modulus HNP is at least 10%less, or at least 20% less, or at least 25% less, or at least 30% less,or at least 35% less, than the modulus of the high modulus HNP.

Low modulus HNPs of the present invention are salts of acid copolymers.It is understood that the low modulus HNP may be a blend of two or morelow modulus HNPs. The acid copolymer of the low modulus HNP is anO/X/Y-type copolymer, wherein O is an α-olefin, X is a C₃-C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningmonomer. O is preferably ethylene. X is preferably selected from (meth)acrylic acid, ethacrylic acid, maleic acid, crotonic acid, fumaric acid,and itaconic acid. (Meth) acrylic acid is particularly preferred. Asused herein, “(meth) acrylic acid” means methacrylic acid and/or acrylicacid. Likewise, “(meth)acrylate” means methacrylate and/or acrylate. Yis preferably an alkyl (meth)acrylate, wherein the alkyl groups havefrom 1 to 8 carbon atoms. Preferred O/X/Y-type copolymers are thosewherein O is ethylene, X is (meth) acrylic acid, and Y is selected from(meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, methyl(meth)acrylate, and ethyl (meth)acrylate. Particularly preferredO/X/Y-type copolymers are ethylene/(meth) acrylic acid/n-butyl acrylate,ethylene/(meth) acrylic acid/methyl acrylate, and ethylene/(meth)acrylic acid/ethyl acrylate.

The acid copolymer of the low modulus HNP typically includes theα-olefin in an amount of at least 15 wt %, or at least 25 wt %, or atleast 40 wt %, or at least 60 wt %, based on the total weight of theacid copolymer. The amount of C₃-C₈ α,β-ethylenically unsaturatedcarboxylic acid in the acid copolymer is typically within a range havinga lower limit of 1 or 4 or 6 or 8 or 10 or 15 wt % and an upper limit of20 or 35 or 40 wt %, based on the total weight of the acid copolymer.The amount of softening monomer in the acid copolymer is typicallywithin a range having a lower limit of 1 or 3 or 5 or 11 or 15 or 20 wt% and an upper limit of 23 or 25 or 30 or 35 or 50 wt %, based on thetotal weight of the acid copolymer.

Particularly suitable acid copolymers of the low modulus HNP includevery low modulus ionomer- (“VLMI-”) type ethylene-acid polymers, such asSurlyn® 6320, Surlyn® 8120, Surlyn® 8320, and Surlyn® 9320. Surlyn®ionomers are commercially available from E. I. du Pont de Nemours andCompany. Also suitable are DuPont® HPF 1000 and DuPont® HPF 2000,ionomeric materials commercially available from E. I. du Pont de Nemoursand Company.

Additional suitable acid copolymers of the low modulus HNP aredisclosed, for example, in U.S. Patent Application Publication Nos.2005/0148725, 2005/0020741, 2004/0220343, and 2003/0130434, and U.S.Pat. Nos. 5,691,418, 6,562,906, 6,653,382, 6,777,472, 6,762,246, and6,815,480, the entire disclosures of which are hereby incorporatedherein by reference.

In a preferred embodiment, the low modulus HNP is formed by reacting anacid copolymer, which is optionally partially neutralized, with asufficient amount of cation source, in the presence of a high molecularweight organic acid or salt thereof, such that at least 80%, preferablyat least 90%, more preferably at least 95%, and even more preferably100%, of all acid groups present are neutralized. The acid copolymer canbe reacted with the high molecular weight organic acid or salt thereofand the cation source simultaneously, or the acid copolymer can bereacted with the high molecular weight organic acid prior to theaddition of the cation source.

Suitable high molecular weight organic acids are aliphatic organicacids, aromatic organic acids, saturated monofunctional organic acids,unsaturated monofunctional organic acids, multi-unsaturatedmonofunctional organic acids, and dimerized derivatives thereof.Particular examples of suitable organic acids include, but are notlimited to, caproic acid, caprylic acid, capric acid, lauric acid,stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid,myristic acid, benzoic acid, palmitic acid, phenylacetic acid,naphthalenoic acid, dimerized derivatives thereof, and combinationsthereof. Salts of high molecular weight organic acids comprise thesalts, particularly the barium, lithium, sodium, zinc, bismuth,chromium, cobalt, copper, potassium, stontium, titanium, tungsten,magnesium, and calcium salts, of aliphatic organic acids, aromaticorganic acids, saturated monofunctional organic acids, unsaturatedmonofunctional organic acids, multi-unsaturated monofunctional organicacids, dimerized derivatives thereof, and combinations thereof. Suitableorganic acids and salts thereof are more fully described, for example,in U.S. Pat. No. 6,756,436, the entire disclosure of which is herebyincorporated herein by reference.

Suitable cation sources include metal ions and compounds of alkalimetals, alkaline earth metals, and transition metals; metal ions andcompounds of rare earth elements; silicone, silane, and silicatederivatives and complex ligands; and combinations thereof. Preferredcation sources are metal ions and compounds of magnesium, sodium,potassium, cesium, calcium, barium, manganese, copper, zinc, tin,lithium, and rare earth metals. The acid copolymer may be at leastpartially neutralized prior to contacting the acid copolymer with thecation source to form the low modulus HNP. Methods of preparing ionomersare well known, and are disclosed, for example, in U.S. Pat. No.3,264,272, the entire disclosure of which is hereby incorporated hereinby reference. The acid copolymer can be a direct copolymer wherein thepolymer is polymerized by adding all monomers simultaneously, asdisclosed, for example, in U.S. Pat. No. 4,351,931, the entiredisclosure of which is hereby incorporated herein by reference.Alternatively, the acid copolymer can be a graft copolymer wherein amonomer is grafted onto an existing polymer, as disclosed, for example,in U.S. Patent Application Publication No. 2002/0013413, the entiredisclosure of which is hereby incorporated herein by reference.

Low modulus HNP compositions of the present invention optionally containone or more melt flow modifiers. The amount of melt flow modifier in thecomposition is readily determined such that the melt flow index of thecomposition is at least 0.1 g/10 min, preferably from 0.5 g/10 min to10.0 g/10 min, and more preferably from 1.0 g/10 min to 6.0 g/10 min, asmeasured using ASTM D-1238, condition E, at 190° C., using a 2160 gramweight.

Suitable melt flow modifiers include, but are not limited to, highmolecular weight organic acids and salts thereof, polyamides,polyesters, polyacrylates, polyurethanes, polyethers, polyureas,polyhydric alcohols, and combinations thereof. Suitable organic acidsare aliphatic organic acids, aromatic organic acids, saturatedmono-functional organic acids, unsaturated monofunctional organic acids,multi-unsaturated mono-functional organic acids, and dimerizedderivatives thereof. Particular examples of suitable organic acidsinclude, but are not limited to, caproic acid, caprylic acid, capricacid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid,linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylaceticacid, naphthalenoic acid, dimerized derivatives thereof. Suitableorganic acids are more fully described, for example, in U.S. Pat. No.6,756,436, the entire disclosure of which is hereby incorporated hereinby reference.

Additional melt flow modifiers suitable for use in compositions of thepresent invention, include the non-fatty acid melt flow modifiersdescribed in copending U.S. patent application Ser. Nos. 11/216,725 and11/216,726, the entire disclosures of which are hereby incorporatedherein by reference.

Low modulus HNP compositions of the present invention optionally includeadditive(s) and/or filler(s) in an amount of 50 wt % or less, or 30 wt %or less, or 15 wt % or less, based on the total weight of the lowmodulus HNP composition. Suitable additives and fillers include, but arenot limited to, chemical blowing and foaming agents, opticalbrighteners, coloring agents, fluorescent agents, whitening agents, UVabsorbers, light stabilizers, defoaming agents, processing aids, mica,talc, nano-fillers, antioxidants, stabilizers, softening agents,fragrance components, plasticizers, impact modifiers, TiO₂, acidcopolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide,barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinccarbonate, barium carbonate, clay, tungsten, tungsten carbide, silica,lead silicate, regrind (recycled material), and mixtures thereof.Suitable additives are more fully described in, for example, U.S. PatentApplication Publication No. 2003/0225197, the entire disclosure of whichis hereby incorporated herein by reference.

Low modulus HNP compositions of the present invention optionally containa high modulus HNP.

Low modulus HNP compositions of the present invention preferably have amaterial hardness within a range having a lower limit of 40 or 50 or 55Shore C and an upper limit of 70 or 80 or 87 Shore C.

In a particular embodiment, the low modulus HNP composition has amoisture vapor transmission rate of 8 g-mil/100 in²/day or less (i.e.,3.2 g-mm/m²·day or less), or 5 g-mil/100 in²/day or less (i.e., 2.0g-mm/m²·day or less), or 3 g-mil/100 in²/day or less (i.e., 1.2g-mm/m²·day or less), or 2 g-mil/100 in²/day or less (i.e., 0.8g-mm/m²·day or less), or 1 g-mil/100 in²/day or less (i.e., 0.4g-mm/m²·day or less), or less than 1 g-mil/100 in²/day (i.e., less than0.4 g-mm/m²·day). As used herein, moisture vapor transmission rate(“MVTR”) is given in g-mil/100 in²/day, and is measured at 20° C. andaccording to ASTM F1249-99. In a preferred aspect of this embodiment,the low modulus HNP composition comprises a low modulus HNP preparedusing a cation source which is less hydrophilic than conventionalmagnesium-based cation sources. Suitable moisture resistant HNPcompositions are disclosed, for example, in U.S. Patent ApplicationPublication Nos. 2005/0267240, 2006/0106175 and 2006/0293464, the entiredisclosures of which are hereby incorporated herein by reference.

In another particular embodiment, a sphere formed from the low modulusHNP composition has a compression of 80 or less, or 70 or less, or 65 orless, or 60 or less, or 50 or less, or 40 or less, or 30 or less, or 20or less.

Low modulus HNP compositions of the present invention are not limited byany particular method or any particular equipment for making thecompositions. In a preferred embodiment, the composition is prepared bythe following process. The acid polymer(s), preferably a VLMI-typeethylene-acid terpolymer, high molecular weight organic acid(s) orsalt(s) thereof, and optionally additive(s)/filler(s) are simultaneouslyor individually fed into a melt extruder, such as a single or twin screwextruder. A suitable amount of cation source is simultaneously orsubsequently added such that at least 80%, preferably at least 90%, morepreferably at least 95%, and even more preferably 100%, of all acidgroups present are neutralized. The acid polymer may be at leastpartially neutralized prior to the above process. The components areintensively mixed prior to being extruded as a strand from the die-head.

Low modulus HNP compositions of the present invention may be blendedwith one or more additional polymers, such as thermoplastic polymers andelastomers. Examples of thermoplastic polymers suitable for blendinginclude, but are not limited to, bimodal ionomers (e.g., as disclosed inU.S. Patent Application Publication No. 2004/0220343 and U.S. Pat. Nos.6,562,906, 6,762,246 and 7,273,903, the entire disclosures of which arehereby incorporated herein by reference), ionomers modified with rosins(e.g., as disclosed in U.S. Patent Application Publication No.2005/0020741, the entire disclosure of which is hereby incorporated byreference), soft and resilient ethylene copolymers (e.g., as disclosedU.S. Patent Application Publication No. 2003/0114565, the entiredisclosure of which is hereby incorporated herein by reference)polyolefins, polyamides, polyesters, polyethers, polycarbonates,polysulfones, polyacetals, polylactones, acrylonitrile-butadiene-styreneresins, polyphenylene oxide, polyphenylene sulfide,styrene-acrylonitrile resins, styrene maleic anhydride, polyimides,aromatic polyketones, ionomers and ionomeric precursors, acidcopolymers, conventional HNPs, polyurethanes, grafted and non-graftedmetallocene-catalyzed polymers, single-site catalyst polymerizedpolymers, high crystalline acid polymers, cationic ionomers, andcombinations thereof. Particular polyolefins suitable for blendinginclude one or more, linear, branched, or cyclic, C₂-C₄₀ olefins,particularly polymers comprising ethylene or propylene copolymerizedwith one or more C₂-C₄₀ olefins, C₃-C₂₀ α-olefins, or C₃-C₁₀ α-olefins.Particular conventional HNPs suitable for blending include, but are notlimited to, one or more of the HNPs disclosed in U.S. Pat. Nos.6,756,436, 6,894,098, and 6,953,820, the entire disclosures of which arehereby incorporated herein by reference. Examples of elastomers suitablefor blending with the invention polymers include natural and syntheticrubbers, including, but not limited to, ethylene propylene rubber(“EPR”), ethylene propylene diene rubber (“EPDM”), styrenic blockcopolymer rubbers (such as SI, SIS, SB, SBS, SIBS, and the like, where“S” is styrene, “I” is isobutylene, and “B” is butadiene), butyl rubber,halobutyl rubber, copolymers of isobutylene and para-alkylstyrene,halogenated copolymers of isobutylene and para-alkylstyrene, naturalrubber, polyisoprene, copolymers of butadiene with acrylonitrile,polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber,acrylonitrile chlorinated isoprene rubber, and polybutadiene rubber (cisand trans). Additional suitable blend polymers include those describedin U.S. Pat. No. 5,981,658, for example at column 14, lines 30 to 56,the entire disclosure of which is hereby incorporated herein byreference. The blends described herein may be produced by post-reactorblending, by connecting reactors in series to make reactor blends, or byusing more than one catalyst in the same reactor to produce multiplespecies of polymer. The polymers may be mixed prior to being put into anextruder, or they may be mixed in an extruder.

Particularly suitable low modulus HNP compositions include, but are notlimited to, the highly-resilient thermoplastic compositions disclosed inU.S. Patent Application Publication No. 2005/0148725; thehighly-neutralized ethylene copolymers disclosed in U.S. Pat. Nos.6,653,382 and 6,777,472, and U.S. Patent Application Publication No.2003/0130434; and the highly-resilient thermoplastic elastomercompositions disclosed in U.S. Pat. No. 6,815,480; the entiredisclosures of which are hereby incorporated herein by reference.

High Modulus HNP Composition

High modulus HNP compositions of the present invention comprise at leastone high modulus HNP having a modulus within a range having a lowerlimit of 25,000 or 27,000 or 30,000 or 40,000 or 45,000 or 50,000 or55,000 or 60,000 psi and an upper limit of 72,000 or 75,000 or 100,000or 150,000 psi.

High modulus HNPs of the present invention are salts of acid copolymers.It is understood that the high modulus HNP may be a blend of two or morehigh modulus HNPs. Preferred acid copolymers are copolymers of anα-olefin and a C₃-C₈ α,β-ethylenically unsaturated carboxylic acid. Theacid is typically present in the acid copolymer in an amount within arange having a lower limit of 1 or 10 or 12 or 15 or 20 wt % and anupper limit of 25 or 30 or 35 or 40 wt %, based on the total weight ofthe acid copolymer. The α-olefin is preferably selected from ethyleneand propylene. The acid is preferably selected from (meth) acrylic acid,ethacrylic acid, maleic acid, crotonic acid, fumaric acid, and itaconicacid. (Meth) acrylic acid is particularly preferred. In a preferredembodiment, the high modulus HNP has a higher level of acid than the lowmodulus HNP.

Suitable acid copolymers include partially neutralized acid polymers.Examples of suitable partially neutralized acid polymers include, butare not limited to, Surlyn® ionomers, commercially available from E. I.du Pont de Nemours and Company; AClyn® ionomers, commercially availablefrom Honeywell International Inc.; and Iotek® ionomers, commerciallyavailable from ExxonMobil Chemical Company. Also suitable are DuPont®HPF 1000 and DuPont® HPF 2000, ionomeric materials commerciallyavailable from E. I. du Pont de Nemours and Company. Additional suitableacid polymers are more fully described, for example, in U.S. Pat. Nos.6,562,906, 6,762,246, and 6,953,820 and U.S. Patent ApplicationPublication Nos. 2005/0049367, 2005/0020741, and 2004/0220343, theentire disclosures of which are hereby incorporated herein by reference.

In a preferred embodiment, the high modulus HNP is formed by reacting anacid copolymer with a sufficient amount of cation source such that atleast 80%, preferably at least 90%, more preferably at least 95%, andeven more preferably 100%, of all acid groups present are neutralized.Suitable cation sources include metal ions and compounds of alkalimetals, alkaline earth metals, and transition metals; metal ions andcompounds of rare earth elements; silicone, silane, and silicatederivatives and complex ligands; and combinations thereof. Preferredcation sources are metal ions and compounds of magnesium, sodium,potassium, cesium, calcium, barium, manganese, copper, zinc, tin,lithium, and rare earth metals. Metal ions and compounds of calcium andmagnesium are particularly preferred. The acid copolymer may be at leastpartially neutralized prior to contacting the acid copolymer with thecation source to form the high modulus HNP. As previously stated,methods of preparing ionomers, and the acid copolymers on which ionomersare based, are disclosed, for example, in U.S. Pat. Nos. 3,264,272, and4,351,931, and U.S. Patent Application Publication No. 2002/0013413.

High modulus HNP compositions of the present invention optionallycontain one or more melt flow modifiers. The amount of melt flowmodifier in the composition is readily determined such that the meltflow index of the composition is at least 0.1 g/10 min, preferably from0.5 g/10 min to 10.0 g/10 min, and more preferably from 1.0 g/10 min to6.0 g/10 min, as measured using ASTM D-1238, condition E, at 190° C.,using a 2160 gram weight.

Suitable melt flow modifiers include, but are not limited to, highmolecular weight organic acids and salts thereof, polyamides,polyesters, polyacrylates, polyurethanes, polyethers, polyureas,polyhydric alcohols, and combinations thereof. Suitable organic acidsare aliphatic organic acids, aromatic organic acids, saturatedmono-functional organic acids, unsaturated monofunctional organic acids,multi-unsaturated mono-functional organic acids, and dimerizedderivatives thereof. Particular examples of suitable organic acidsinclude, but are not limited to, caproic acid, caprylic acid, capricacid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid,linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylaceticacid, naphthalenoic acid, dimerized derivatives thereof. Suitableorganic acids are more fully described, for example, in U.S. Pat. No.6,756,436, the entire disclosure of which is hereby incorporated hereinby reference.

Additional melt flow modifiers suitable for use in compositions of thepresent invention, include the non-fatty acid melt flow modifiersdescribed in copending U.S. patent application Ser. Nos. 11/216,725 and11/216,726, the entire disclosures of which are hereby incorporatedherein by reference.

High modulus HNP compositions of the present invention optionallyinclude additive(s) and/or filler(s) in an amount within a range havinga lower limit of 0 or 5 or 10 wt %, and an upper limit of 25 or 30 or 50wt %, based on the total weight of the high modulus HNP composition.Suitable additives and fillers include those previously described assuitable for the low modulus HNP compositions of the present invention.

In addition to the high modulus HNP, optional melt flow modifier(s), andoptional additive(s) and/or filler(s), the high modulus HNP compositionof the present invention may contain a low modulus HNP.

In a particular embodiment, the high modulus HNP composition has an MVTRof 8 g-mil/100 in²/day or less (i.e., 3.2 g-mm/m²·day or less), or 5g-mil/100 in²/day or less (i.e., 2.0 g-mm/m²·day or less), or 3g-mil/100 in²/day or less (i.e., 1.2 g-mm/m²·day or less), or 2g-mil/100 in²/day or less (i.e., 0.8 g-mm/m²·day or less), or 1g-mil/100 in²/day or less (i.e., 0.4 g-mm/m²·day or less), or less than1 g-mil/100 in²/day (i.e., less than 0.4 g-mm/m²·day). In a preferredaspect of this embodiment, the high modulus HNP composition comprises ahigh modulus HNP prepared using a cation source which is lesshydrophilic than conventional magnesium-based cation sources. Suitablemoisture resistant HNP compositions are disclosed, for example, incopending U.S. patent application Ser. No. 11/270,066 and U.S. PatentApplication Publication No. 2005/0267240, the entire disclosures ofwhich are hereby incorporated herein by reference.

In another particular embodiment, a sphere formed from the high modulusHNP composition has a compression of 70 or greater, or 80 or greater, ora compression within a range having a lower limit of 70 or 80 or 90 or100 and an upper limit of 110 or 130 or 140.

High modulus HNP compositions of the present invention are not limitedby any particular method or any particular equipment for making thecompositions. In a preferred embodiment, the composition is prepared bythe following process. The acid polymer(s), preferably anethylene/(meth) acrylic acid copolymer, optional melt flow modifier(s),and optional additive(s)/filler(s) are simultaneously or individuallyfed into a melt extruder, such as a single or twin screw extruder. Asuitable amount of cation source is then added such that at least 80%,preferably at least 90%, more preferably at least 95%, and even morepreferably 100%, of all acid groups present are neutralized. The acidpolymer may be at least partially neutralized prior to the aboveprocess. The components are intensively mixed prior to being extruded asa strand from the die-head.

In another preferred embodiment, the high modulus HNP composition isformed by combining a low modulus HNP with a sufficient amount of one ormore additional material(s), including, but not limited to, additives,fillers, and polymeric materials, to increase the modulus such that theresulting composition has a modulus as described above for the highmodulus HNP.

HNP compositions of the present invention may be blended with one ormore additional polymers, such as thermoplastic polymers and elastomers.Examples of thermoplastic polymers and elastomers suitable for blendinginclude those previously described as suitable for blending with the lowmodulus HNP compositions of the present invention.

HNP compositions of the present invention, in the neat (i.e., unfilled)form, preferably have a specific gravity of from 0.95 g/cc to 0.99 g/cc.Any suitable filler, flake, fiber, particle, or the like, of an organicor inorganic material may be added to the HNP composition to increase ordecrease the specific gravity, particularly to adjust the weightdistribution within the golf ball, as further disclosed in U.S. Pat.Nos. 6,494,795, 6,547,677, 6,743,123, 7,074,137, and 6,688,991, theentire disclosures of which are hereby incorporated herein by reference.

Golf Ball Applications

Golf balls of the present invention comprise at least one layer formedfrom a low modulus HNP composition and at least one layer formed from ahigh modulus HNP composition. In a preferred embodiment, the presentinvention provides a golf ball having a multi-layer core and a cover,wherein the core includes a layer formed from a low modulus HNPcomposition and a layer formed from a high modulus HNP composition.

In the embodiments disclosed herein, the low modulus HNP compositionand/or the high modulus HNP composition can be either foamed or filledwith density adjusting materials to provide desirable golf ballperformance characteristics.

Golf balls having a layer formed from a low modulus HNP composition anda layer formed from a high modulus HNP composition are furtherdisclosed, for example, in U.S. Pat. No. 7,211,008, the entiredisclosure of which is hereby incorporated herein by reference.

The present invention provides a golf ball having a multi-layer core,wherein the core comprises a center, an outer core layer, and anintermediate core layer disposed between the center and the outer corelayer. Each one of the core layers, including the center, may be formedfrom a composition disclosed herein or a blend of compositions disclosedherein, so long as at least one core layer is formed from a low modulusHNP composition and at least one layer is formed from a high modulus HNPcomposition. The multi-layer core optionally comprises two or morelayers formed from the same or different low modulus HNP compositionsand/or two or more layers formed from the same or different high modulusHNP compositions.

In a particular embodiment, the intermediate core layer is formed from ahigh modulus HNP composition and the outer core layer is formed from alow modulus HNP composition. In another particular embodiment, thecenter is formed from a low modulus HNP composition and the intermediatecore layer is formed from a high modulus HNP composition. In anotherparticular embodiment, the center is formed from a low modulus HNPcomposition and the outer core layer is formed from a high modulus HNPcomposition. In yet another particular embodiment, the center is formedfrom a high modulus HNP composition and the outer core layer is formedfrom a low modulus HNP composition.

In embodiments of the present invention wherein the core includes alayer formed from a composition other than a low modulus HNP compositionor a high modulus HNP composition, such layer may be formed from anysuitable golf ball composition. Preferably, the layer that is not formedfrom a low modulus HNP composition or a high modulus HNP composition isformed from a rubber composition or from a highly resilientthermoplastic polymer such as a conventional HNP composition.Particularly suitable thermoplastic polymers include Surlyn® ionomers,Hytrel® thermoplastic polyester elastomers, and ionomeric materials soldunder the trade names DuPont® HPF 1000 and DuPont® HPF 2000, all ofwhich are commercially available from E. I. du Pont de Nemours andCompany; Iotek® ionomers, commercially available from ExxonMobilChemical Company; and Pebax® thermoplastic polyether block amides,commercially available from Arkema Inc. Suitable rubber andthermoplastic polymer compositions are further disclosed below.

In one embodiment, the present invention is directed to a golf ballcomprising a center, an outer core layer, an intermediate core layerdisposed between the center and the outer core layer, and one or morecover layers. In a particular aspect of this embodiment, the golf ballhas one or more of the following properties:

-   -   (a) a center having a diameter within a range having a lower        limit of 0.250 or 0.500 or 0.600 or 0.750 or 0.800 or 1.000 or        1.100 or 1.200 inches and an upper limit of 1.300 or 1.350 or        1.400 or 1.500 or 1.510 or 1.530 or 1.550 or 1.570 or 1.580 or        1.600 inches;    -   (b) an intermediate core layer having a thickness within a range        having a lower limit of 0.020 or 0.025 or 0.032 or 0.050 or        0.075 or 0.100 or 0.125 inches and an upper limit of 0.150 or        0.175 or 0.200 or 0.220 or 0.250 or 0.280 or 0.300 inches;    -   (c) an outer core layer having a thickness within a range having        a lower limit of 0.010 or 0.020 or 0.025 or 0.030 or 0.032        inches and an upper limit of 0.070 or 0.080 or 0.100 or 0.150 or        0.310 or 0.440 or 0.560 inches;    -   (d) an intermediate core layer and an outer core layer having a        combined thickness within a range having a lower limit of 0.040        inches and an upper limit of 0.560 or 0.800 inches;    -   (e) an outer core layer having a thickness such that a golf ball        subassembly including the center, intermediate core layer, and        core layer has an outer diameter within a range having a lower        limit of 1.000 or 1.300 or 1.400 or 1.450 or 1.500 or 1.510 or        1.530 or 1.550 inches and an upper limit of 1.560 or 1.570 or        1.580 or 1.590 or 1.600 or 1.620 or 1.640 inches;    -   (f) a center having a surface hardness of 65 Shore C or greater,        or 70 Shore C or greater, or a surface hardness within a range        having a lower limit of 55 or 60 or 65 or 70 or 75 Shore C and        an upper limit of 80 or 85 Shore C;    -   (g) a center having a center hardness (H) within a range having        a lower limit of 20 or 25 or 30 or 35 or 45 or 50 or 55 Shore C        and an upper limit of 60 or 65 or 70 or 75 or 90 Shore C; an        outer core layer having a surface hardness (S) within a range        having a lower limit of 20 or 25 or 30 or 35 or 45 or 55 Shore C        and an upper limit of 60 or 70 or 75 or 90 Shore C; and        -   (i) H═S;        -   (ii) H<S, and the difference between H and S is from −15 to            40, preferably from −15 to 22, more preferably from −10 to            15, and even more preferably from −5 to 10; or        -   (iii) S<H, and the difference between H and S is from −15 to            40, preferably from −15 to 22, more preferably from −10 to            15, and even more preferably from −5 to 10;    -   (h) an intermediate layer having a surface hardness (I) that is        greater than both the center hardness of the center (H) and the        surface hardness of the outer core layer (S); I is preferably 40        Shore C or greater or within a range having an lower limit of 40        or 45 or 50 or 85 Shore C and an upper limit of 90 or 93 or 95        Shore C; the Shore D range for I is preferably from 40 to 80,        more preferably from 50 to 70;    -   (i) each core layer having a specific gravity of from 0.50 g/cc        to 5.00 g/cc; preferably from 1.05 g/cc to 1.25 g/cc; more        preferably from 1.10 g/cc to 1.18 g/cc;    -   (j) a center having a surface hardness greater than or equal to        the center hardness of the center;    -   (k) a center having a positive hardness gradient wherein the        surface hardness of the center is at least 10 Shore C units        greater than the center hardness of the center;    -   (l) an outer core layer having a surface hardness greater than        or equal to the surface hardness and center hardness of the        center;    -   (m) a center having a compression of 40 or less;    -   (n) a center having a compression of from 20 to 40; and    -   (o) a golf ball subassembly including the center and the        intermediate core layer has a compression of 30 or greater, or        40 or greater, or 50 or greater, or 60 or greater, or a        compression within a range having a lower limit of 30 or 40 or        50 or 60 and an upper limit of 65 or 75 or 85 or 95 or 105.

The weight distribution of cores disclosed herein can be varied toachieve certain desired parameters, such as spin rate, compression, andinitial velocity.

Golf ball cores of the present invention typically have an overall corecompression of less than 100, or a compression of 87 or less, or anoverall core compression within a range having a lower limit of 20 or 50or 60 or 65 or 70 or 75 and an upper limit of 80 or 85 or 90 or 100 or110 or 120, or an overall core compression of about 80. Compression isan important factor in golf ball design. For example, the compression ofthe core can affect the ball's spin rate off the driver and the feel. Asdisclosed in Jeff Dalton's Compression by Any Other Name, Science andGolf IV, Proceedings of the World Scientific Congress of Golf (EricThain ed., Routledge, 2002) (“J. Dalton”), several different methods canbe used to measure compression, including Atti compression, Riehlecompression, load/deflection measurements at a variety of fixed loadsand offsets, and effective modulus. For purposes of the presentinvention, “compression” refers to Atti compression and is measuredaccording to a known procedure, using an Atti compression test device,wherein a piston is used to compress a ball against a spring. The travelof the piston is fixed and the deflection of the spring is measured. Themeasurement of the deflection of the spring does not begin with itscontact with the ball; rather, there is an offset of approximately thefirst 1.25 mm (0.05 inches) of the spring's deflection. Very lowstiffness cores will not cause the spring to deflect by more than 1.25mm and therefore have a zero compression measurement. The Atticompression tester is designed to measure objects having a diameter of42.7 mm (1.68 inches); thus, smaller objects, such as golf ball cores,must be shimmed to a total height of 42.7 mm to obtain an accuratereading. Conversion from Atti compression to Riehle (cores), Riehle(balls), 100 kg deflection, 130-10 kg deflection or effective moduluscan be carried out according to the formulas given in J. Dalton.

Golf ball cores of the present invention typically have a coefficient ofrestitution (“COR”) at 125 ft/s of at least 0.75, preferably at least0.78, and more preferably at least 0.79. COR, as used herein, isdetermined according to a known procedure wherein a golf ball or golfball subassembly (e.g., a golf ball core) is fired from an air cannon ata given velocity (125 ft/s for purposes of the present invention).Ballistic light screens are located between the air cannon and the steelplate to measure ball velocity. As the ball travels toward the steelplate, it activates each light screen, and the time at each light screenis measured. This provides an incoming transit time period proportionalto the ball's incoming velocity. The ball impacts the steel plate andrebounds though the light screens, which again measure the time periodrequired to transit between the light screens. This provides an outgoingtransit time period proportional to the ball's outgoing velocity. COR isthen calculated as the ratio of the outgoing transit time period to theincoming transit time period, COR=T_(out)/T_(in).

Cores of the present invention are enclosed with a cover, which may be asingle-, dual-, or multi-layer cover.

Suitable cover layer materials for the golf balls disclosed hereininclude, but are not limited to, ionomer resin and blends thereof(particularly Surlyn® ionomer resin), polyurethanes, polyureas,(meth)acrylic acid, thermoplastic rubber polymers, polyethylene, andsynthetic or natural vulcanized rubber, such as balata. Suitablecommercially available ionomeric cover materials include, but are notlimited to, Surlyn® ionomer resins and DuPont® HPF 1000 and HPF 2000,commercially available from E. I. du Pont de Nemours and Company; andIotek® ionomers, commercially available from ExxonMobil ChemicalCompany.

Particularly suitable outer cover layer materials include relativelysoft polyurethanes and polyureas. When used as cover layer materials,polyurethanes and polyureas can be thermoset or thermoplastic. Thermosetmaterials can be formed into golf ball layers by conventional casting orreaction injection molding techniques. Thermoplastic materials can beformed into golf ball layers by conventional compression or injectionmolding techniques. Light stable polyureas and polyurethanes arepreferred for the outer cover layer material. In embodiments of thepresent invention wherein a golf ball having a single layer cover isprovided, the cover layer material is preferably selected frompolyurethane and polyurea. In embodiments of the present inventionwherein a golf ball having a dual cover is provided, the inner coverlayer is preferably a high modulus thermoplastic, and the outer coverlayer is preferably selected from polyurethane and polyurea.

Suitable cover layer materials also include blends of ionomers withthermoplastic elastomers. Suitable ionomeric cover materials are furtherdisclosed, for example, in U.S. Pat. Nos. 6,653,382, 6,756,436,6,894,098, 6,919,393, and 6,953,820, the entire disclosures of which arehereby incorporated by reference. Suitable polyurethane cover materialsare further disclosed in U.S. Pat. Nos. 5,334,673, 6,506,851, 6,756,436,and 7,105,623, the entire disclosures of which are hereby incorporatedherein by reference. Suitable polyurea cover materials are furtherdisclosed in U.S. Pat. Nos. 5,484,870 and 6,835,794, the entiredisclosures of which are hereby incorporated herein by reference.Suitable polyurethane-urea hybrids are blends or copolymers comprisingurethane or urea segments as disclosed in U.S. Patent ApplicationPublication No. 2007/0117923, the entire disclosure of which is herebyincorporated herein by reference. Additional suitable cover materialsare disclosed, for example, in U.S. Patent Application Publication No.2005/0164810, U.S. Pat. No. 5,919,100, and PCT Publications WO00/23519and WO00/29129, the entire disclosures of which are hereby incorporatedherein by reference.

The ionomeric composition of the inner cover layer is preferablyselected from:

-   -   (a) a composition comprising a “high acid ionomer” (i.e., having        an acid content of greater than 16 wt %), such as Surlyn 8150®,        a copolymer of ethylene and methacrylic acid, having an acid        content of 19 wt %, which is 45% neutralized with sodium,        commercially available from E. I. du Pont de Nemours and        Company;    -   (b) a composition comprising a high acid ionomer and a maleic        anhydride-grafted non-ionomeric polymer (e.g., Fusabond 572D®, a        maleic anhydride-grafted, metallocene-catalyzed ethylene-butene        copolymer having about 0.9 wt % maleic anhydride grafted onto        the copolymer, commercially available from E. I. du Pont de        Nemours and Company). A particularly preferred blend of high        acid ionomer and maleic anhydride-grafted polymer is a 84 wt        %/16 wt % blend of Surlyn 8150® and Fusabond 572D®. Blends of        high acid ionomers with maleic anhydride-grafted polymers are        further disclosed, for example, in U.S. Pat. Nos. 6,992,135 and        6,677,401, the entire disclosures of which are hereby        incorporated herein by reference;    -   (c) a composition comprising a 50/45/5 blend of Surlyn®        8940/Surlyn® 9650/Nucrel® 960, preferably having a material        hardness of from 80 to 85 Shore C;    -   (d) a composition comprising a 50/25/25 blend of Surlyn®        8940/Surlyn® 9650/Surlyn® 9910, preferably having a material        hardness of about 90 Shore C; and    -   (e) a composition comprising a 50/50 blend of Surlyn®        8940/Surlyn® 9650, preferably having a material hardness of        about 86 Shore C.

Surlyn® 8940 is an E/MAA copolymer in which the MAA acid groups havebeen partially neutralized with sodium ions. Surlyn® 9650 and Surlyn®9910 are two different grades of E/MAA copolymer in which the MAA acidgroups have been partially neutralized with zinc ions. Nucrel® 960 is anE/MAA copolymer resin nominally made with 15 wt % methacrylic acid.Surlyn® 8940, Surlyn® 9650, Surlyn® 9910, and Nucrel® 960 arecommercially available from E. I. du Pont de Nemours and Company.

Non-limiting examples of preferred inner cover layer materials are shownin the Examples below.

The inner cover layer material may include a flow modifier, such as, butnot limited to, Nucrel® acid copolymer resins, and particularly Nucrel®960. Nucrel® acid copolymer resins are commercially available from E. I.du Pont de Nemours and Company.

The outer cover layer is preferably formed from a composition comprisingpolyurethane, polyurea, or a copolymer or hybrid ofpolyurethane/polyurea. The outer cover layer material may bethermoplastic or thermoset.

In a particular embodiment, the cover is a single layer preferablyformed from an ionomeric composition. The single layer cover preferablyhas a surface hardness of 65 Shore D or less, or 60 Shore D or less, or45 Shore D or less, or 40 Shore D or less, or from 25 Shore D to 40Shore D, or from 30 Shore D to 40 Shore D and a thickness within a rangehaving a lower limit of 0.010 or 0.015 or 0.020 or 0.025 or 0.030 or0.055 or 0.060 inches and an upper limit of 0.065 or 0.080 or 0.090 or0.100 or 0.110 or 0.120 or 0.140 inches. The flexural modulus of thecover, as measured by ASTM D6272-98 Procedure B, is preferably 500 psior greater, or from 500 psi to 150,000 psi.

In another particular embodiment, the cover is a two-layer coverconsisting of an inner cover layer and an outer cover layer. The innercover layer is preferably formed from an ionomeric composition andpreferably has a surface hardness of 60 Shore D or greater, or a surfacehardness within a range having a lower limit of 30 or 40 or 55 or 60 or65 Shore D and an upper limit of 66 or 68 or 70 or 75 Shore D, and athickness within a range having a lower limit of 0.010 or 0.015 or 0.020or 0.030 inches and an upper limit of 0.035 or 0.040 or 0.045 or 0.050or 0.055 or 0.075 or 0.080 or 0.100 or 0.110 or 0.120 inches. The innercover layer composition preferably has a material hardness of 95 Shore Cor less, or less than 95 Shore C, or 92 Shore C or less, or 90 Shore Cor less, or has a material hardness within a range having a lower limitof 70 or 75 or 80 or 84 or 85 Shore C and an upper limit of 90 or 92 or95 Shore C. The outer cover layer is preferably formed from a castableor reaction injection moldable polyurethane, polyurea, or copolymer orhybrid of polyurethane/polyurea. Such cover material is preferablythermosetting, but may be thermoplastic. The outer cover layercomposition preferably has a material hardness of 85 Shore C or less, or45 Shore D or less, or 40 Shore D or less, or from 25 Shore D to 40Shore D, or from 30 Shore D to 40 Shore D. The outer cover layerpreferably has a surface hardness within a range having a lower limit of20 or 30 or 35 or 40 Shore D and an upper limit of 52 or 58 or 60 or 65or 70 or 72 or 75 Shore D. The outer cover layer preferably has athickness within a range having a lower limit of 0.010 or 0.015 or 0.025inches and an upper limit of 0.035 or 0.040 or 0.045 or 0.050 or 0.055or 0.075 or 0.080 or 0.115 inches. The two-layer cover preferably has anoverall thickness within a range having a lower limit of 0.010 or 0.015or 0.020 or 0.025 or 0.030 or 0.055 or 0.060 inches and an upper limitof 0.065 or 0.075 or 0.080 or 0.090 or 0.100 or 0.110 or 0.120 or 0.140inches.

A moisture vapor barrier layer is optionally employed between the coreand the cover. Moisture vapor barrier layers are further disclosed, forexample, in U.S. Pat. Nos. 6,632,147, 6,932,720, 7,004,854, and7,182,702, the entire disclosures of which are hereby incorporatedherein by reference.

The present invention is not limited by any particular process forforming the golf ball layer(s). It should be understood that thelayer(s) can be formed by any suitable technique, including injectionmolding, compression molding, casting, and reaction injection molding.

When injection molding is used, the composition is typically in apelletized or granulated form that can be easily fed into the throat ofan injection molding machine wherein it is melted and conveyed via ascrew in a heated barrel at temperatures of from 150° F. to 600° F.,preferably from 200° F. to 500° F. The molten composition is ultimatelyinjected into a closed mold cavity, which may be cooled, at ambient orat an elevated temperature, but typically the mold is cooled to atemperature of from 50° F. to 70° F. After residing in the closed moldfor a time of from 1 second to 300 seconds, preferably from 20 secondsto 120 seconds, the core and/or core plus one or more additional core orcover layers is removed from the mold and either allowed to cool atambient or reduced temperatures or is placed in a cooling fluid such aswater, ice water, dry ice in a solvent, or the like.

When compression molding is used to form a center, the composition isfirst formed into a preform or slug of material, typically in acylindrical or roughly spherical shape at a weight slightly greater thanthe desired weight of the molded core. Prior to this step, thecomposition may be first extruded or otherwise melted and forced througha die after which it is cut into a cylindrical preform. It is thatpreform that is then placed into a compression mold cavity andcompressed at a mold temperature of from 150° F. to 400° F., preferablyfrom 250° F. to 350° F., and more preferably from 260° F. to 295° F.When compression molding a core or cover layer of an HNP composition, ahalf-shell is first formed via injection molding and then a corecomprising one or more layers is enclosed within two half shells andthen compression molded in a similar manner to the process previouslydescribed.

Reaction injection molding processes are further disclosed, for example,in U.S. Pat. Nos. 6,083,119, 7,338,391, 7,282,169, 7,281,997 and U.S.Patent Application Publication No. 2006/0247073, the entire disclosuresof which are hereby incorporated herein by reference.

Golf balls of the present invention typically have a compression of 120or less, or a compression within a range having a lower limit of 40 or50 or 60 or 65 or 75 or 80 or 90 and an upper limit of 95 or 100 or 105or 110 or 115 or 120. Golf balls of the present invention typically havea COR at 125 ft/s of at least 0.70, preferably at least 0.75, morepreferably at least 0.78, and even more preferably at least 0.79.

Golf balls of the present invention will typically have dimple coverageof 60% or greater, preferably 65% or greater, and more preferably 75% orgreater. The United States Golf Association specifications limit theminimum size of a competition golf ball to 1.680 inches. There is nospecification as to the maximum diameter, and golf balls of any size canbe used for recreational play. Golf balls of the present invention canhave an overall diameter of any size. The preferred diameter of thepresent golf balls is from 1.680 inches to 1.800 inches. Morepreferably, the present golf balls have an overall diameter of from1.680 inches to 1.760 inches, and even more preferably from 1.680 inchesto 1.740 inches.

Golf balls of the present invention preferably have a moment of inertia(“MOI”) of 70-95 g·cm², preferably 75-93 g·cm², and more preferably76-90 g·cm². For low MOI embodiments, the golf ball preferably has anMOI of 85 g·cm² or less, or 83 g·cm² or less. For high MOI embodiment,the golf ball preferably has an MOI of 86 g·cm² or greater, or 87 g·cm²or greater. MOI is measured on a model MOI-005-104 Moment of InertiaInstrument manufactured by Inertia Dynamics of Collinsville, Conn. Theinstrument is connected to a PC for communication via a COMM port and isdriven by MOI Instrument Software version #1.2.

Thermoplastic layers herein may be treated in such a manner as to createa positive or negative hardness gradient. In golf ball layers of thepresent invention wherein a thermosetting rubber is used,gradient-producing processes and/or gradient-producing rubberformulation may be employed. Gradient-producing processes andformulations are disclosed more fully, for example, in U.S. patentapplication Ser. Nos. 12/048,665, filed on Mar. 14, 2008; U.S. patentapplication Ser. No. 11/829,461, filed on Jul. 27, 2007; U.S. patentapplication Ser. No. 11/772,903, filed Jul. 3, 2007; U.S. patentapplication Ser. No. 11/832,163, filed Aug. 1, 2007; U.S. patentapplication Ser. No. 11/832,197, filed on Aug. 1, 2007; the entiredisclosure of each of these references is hereby incorporated herein byreference.

In addition to the materials disclosed above, any of the core or coverlayers may comprise one or more of the following materials:thermoplastic elastomer, thermoset elastomer, synthetic rubber,thermoplastic vulcanizate, copolymeric ionomer, terpolymeric ionomer,polycarbonate, polyolefin, polyamide, copolymeric polyamide, polyesters,polyester-amides, polyether-amides, polyvinyl alcohols,acrylonitrile-butadiene-styrene copolymers, polyarylate, polyacrylate,polyphenylene ether, impact-modified polyphenylene ether, high impactpolystyrene, diallyl phthalate polymer, metallocene-catalyzed polymers,styrene-acrylonitrile (SAN), olefin-modified SAN,acrylonitrile-styrene-acrylonitrile, styrene-maleic anhydride (S/MA)polymer, styrenic copolymer, functionalized styrenic copolymer,functionalized styrenic terpolymer, styrenic terpolymer, cellulosepolymer, liquid crystal polymer (LCP), ethylene-propylene-diene rubber(EPDM), ethylene-vinyl acetate copolymer (EVA), ethylene propylenerubber (EPR), ethylene vinyl acetate, polyurea, and polysiloxane.Suitable polyamides for use as an additional material in compositionsdisclosed herein also include resins obtained by: (1) polycondensationof (a) a dicarboxylic acid, such as oxalic acid, adipic acid, sebacicacid, terephthalic acid, isophthalic acid or 1,4-cyclohexanedicarboxylicacid, with (b) a diamine, such as ethylenediamine,tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, ordecamethylenediamine, 1,4-cyclohexyldiamine or m-xylylenediamine; (2) aring-opening polymerization of cyclic lactam, such as ε-caprolactam orω-laurolactam; (3) polycondensation of an aminocarboxylic acid, such as6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid or12-aminododecanoic acid; or (4) copolymerzation of a cyclic lactam witha dicarboxylic acid and a diamine. Specific examples of suitablepolyamides include Nylon 6, Nylon 66, Nylon 610, Nylon 11, Nylon 12,copolymerized Nylon, Nylon MXD6, and Nylon 46.

In embodiments of the present invention wherein at least one layer isformed from a rubber composition, suitable rubber compositions includenatural and synthetic rubbers, including, but not limited to,polybutadiene, polyisoprene, ethylene propylene rubber (“EPR”), ethylenepropylene diene rubber (“EPDM”), styrenic block copolymer rubbers (suchas SI, SIS, SB, SBS, SIBS, and the like, where “S” is styrene, “I” isisobutylene, and “B” is butadiene), butyl rubber, halobutyl rubber,copolymers of isobutylene and para-alkylstyrene, halogenated copolymersof isobutylene and para-alkylstyrene, copolymers of butadiene withacrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinatedisoprene rubber, acrylonitrile chlorinated isoprene rubber, andcombinations of two or more thereof. Diene rubbers are preferred,particularly polybutadienes and mixtures of polybutadiene with otherelastomers, and especially 1,4-polybutadiene having a cis-structure ofat least 40%. In a particularly preferred embodiment, the rubbercomposition is a reaction product of a diene rubber, a crosslinkingagent, a filler, a co-crosslinking agent or free radical initiator, andoptionally a cis-to-trans catalyst. The rubber is preferably selectedfrom polybutadiene and styrene-butadiene. The crosslinking agenttypically includes a metal salt, such as a zinc-, aluminum-, sodium-,lithium-, nickel-, calcium-, or magnesium salt, of an unsaturated fattyacid or monocarboxylic acid, such as (meth) acrylic acid. Preferredcrosslinking agents include zinc acrylate, zinc diacrylate (ZDA), zincmethacrylate, and zinc dimethacrylate (ZDMA), and mixtures thereof. Thecrosslinking agent is present in an amount sufficient to crosslink aportion of the chains of the polymers in the composition. Thecrosslinking agent is generally present in the rubber composition in anamount of from 15 to 30 phr, or from 19 to 25 phr, or from 20 to 24 phr.The desired compression may be obtained by adjusting the amount ofcrosslinking, which can be achieved, for example, by altering the typeand amount of crosslinking agent. The free radical initiator can be anyknown polymerization initiator which decomposes during the cure cycle,including, but not limited to, dicumyl peroxide, 1,1-di-(t-butylperoxy)3,3,5-trimethyl cyclohexane, a-a bis-(t-butylperoxy) diisopropylbenzene,2,5-dimethyl-2,5 di-(t-butylperoxy) hexane or di-t-butyl peroxide, andmixtures thereof. The rubber composition optionally contains one or moreantioxidants. Antioxidants are compounds that can inhibit or prevent theoxidative degradation of the rubber. Suitable antioxidants include, forexample, dihydroquinoline antioxidants, amine type antioxidants, andphenolic type antioxidants. The rubber composition may also contain oneor more fillers to adjust the density and/or specific gravity of thecore or cover. Fillers are typically polymeric or mineral particles.Exemplary fillers include precipitated hydrated silica, clay, talc,asbestos, glass fibers, aramid fibers, mica, calcium metasilicate,barium sulfate, zinc sulfide, lithopone, silicates, silicon carbide,diatomaceous earth, polyvinyl chloride, carbonates (e.g., calciumcarbonate and magnesium carbonate), metals (e.g., titanium, tungsten,aluminum, bismuth, nickel, molybdenum, iron, lead, copper, boron,cobalt, beryllium, zinc, and tin), metal alloys (e.g., steel, brass,bronze, boron carbide whiskers, and tungsten carbide whiskers), metaloxides (e.g., zinc oxide, iron oxide, aluminum oxide, titanium oxide,magnesium oxide, and zirconium oxide), particulate carbonaceousmaterials (e.g., graphite, carbon black, cotton flock, natural bitumen,cellulose flock, and leather fiber), microballoons (e.g., glass andceramic), fly ash, regrind, nanofillers and combinations thereof. Therubber composition may also contain one or more additives selected fromfree radical scavengers, accelerators, scorch retarders, coloringagents, fluorescent agents, chemical blowing and foaming agents,defoaming agents, stabilizers, softening agents, impact modifiers,plasticizers, and the like. The rubber composition may also contain asoft and fast agent, such as those disclosed in U.S. patent applicationSer. No. 11/972,240, the entire disclosure of which is herebyincorporated herein by reference. Examples of commercially availablepolybutadienes suitable for use in forming golf ball core layers of thepresent invention include, but are not limited to, Buna CB23,commercially available from LANXESS Corporation; SE BR-1220,commercially available from The Dow Chemical Company; Europrene® NEOCIS®BR 40 and BR 60, commercially available from Polimeri Europa; UBEPOL-BR®rubbers, commercially available from UBE Industries, Ltd.; and BR 01commercially available from Japan Synthetic Rubber Co., Ltd. Suitabletypes and amounts of rubber, crosslinking agent, filler, co-crosslinkingagent, initiator and additives are more fully described in, for example,U.S. Patent Application Publication No. 2004/0214661, 2003/0144087, and2003/0225197, and U.S. Pat. Nos. 6,566,483, 6,695,718, and 6,939,907,the entire disclosures of which are hereby incorporated herein byreference.

In embodiments of the present invention wherein at least one layer isformed from a conventional HNP composition, suitable HNP compositionscomprise an HNP and optionally additives, fillers, and/or melt flowmodifiers. Suitable HNPs are salts of homopolymers and copolymers ofα,β-ethylenically unsaturated mono- or dicarboxylic acids, andcombinations thereof, optionally including a softening monomer. The acidpolymer is neutralized to 70% or higher, including up to 100%, with asuitable cation source. Suitable additives and fillers include, forexample, blowing and foaming agents, optical brighteners, coloringagents, fluorescent agents, whitening agents, UV absorbers, lightstabilizers, defoaming agents, processing aids, mica, talc, nanofillers,antioxidants, stabilizers, softening agents, fragrance components,plasticizers, impact modifiers, acid copolymer wax, surfactants;inorganic fillers, such as zinc oxide, titanium dioxide, tin oxide,calcium oxide, magnesium oxide, barium sulfate, zinc sulfate, calciumcarbonate, zinc carbonate, barium carbonate, mica, talc, clay, silica,lead silicate, and the like; high specific gravity metal powder fillers,such as tungsten powder, molybdenum powder, and the like; regrind, i.e.,core material that is ground and recycled; and nano-fillers. Suitablemelt flow modifiers include, for example, fatty acids and salts thereof,polyamides, polyesters, polyacrylates, polyurethanes, polyethers,polyureas, polyhydric alcohols, and combinations thereof. Suitable HNPcompositions also include blends of HNPs with partially neutralizedionomers as disclosed, for example, in U.S. Patent ApplicationPublication No. 2006/0128904, the entire disclosure of which is herebyincorporated herein by reference, and blends of HNPs with additionalthermoplastic and thermoset materials, including, but not limited to,ionomers, acid copolymers, engineering thermoplastics, fattyacid/salt-based highly neutralized polymers, polybutadienes,polyurethanes, polyesters, thermoplastic elastomers, and otherconventional polymeric materials. Suitable HNP compositions are furtherdisclosed, for example, in U.S. Pat. Nos. 6,653,382, 6,756,436,6,777,472, 6,894,098, 6,919,393, and 6,953,820, the entire disclosuresof which are hereby incorporated herein by reference.

Other preferred materials suitable for use as an additional material ingolf ball compositions disclosed herein include Skypel polyesterelastomers, commercially available from SK Chemicals of South Korea;Septon® diblock and triblock copolymers, commercially available fromKuraray Corporation of Kurashiki, Japan; and Kraton® diblock andtriblock copolymers, commercially available from Kraton Polymers LLC ofHouston, Tex.

Ionomers are also well suited for blending with compositions disclosedherein. Suitable ionomeric polymers include α-olefin/unsaturatedcarboxylic acid copolymer- or terpolymer-type ionomeric resins.Copolymeric ionomers are obtained by neutralizing at least a portion ofthe carboxylic groups in a copolymer of an α-olefin and anα,β-unsaturated carboxylic acid having from 3 to 8 carbon atoms, with ametal ion. Terpolymeric ionomers are obtained by neutralizing at least aportion of the carboxylic groups in a terpolymer of an α-olefin, anα,β-unsaturated carboxylic acid having from 3 to 8 carbon atoms, and anα,β-unsaturated carboxylate having from 2 to 22 carbon atoms, with ametal ion. Examples of suitable α-olefins for copolymeric andterpolymeric ionomers include ethylene, propylene, 1-butene, and1-hexene. Examples of suitable unsaturated carboxylic acids forcopolymeric and terpolymeric ionomers include acrylic, methacrylic,ethacrylic, α-chloroacrylic, crotonic, maleic, fumaric, and itaconicacid. Copolymeric and terpolymeric ionomers include ionomers havingvaried acid contents and degrees of acid neutralization, neutralized bymonovalent or bivalent cations as disclosed herein. Examples ofcommercially available ionomers suitable for blending with compositionsdisclosed herein include Surlyn® ionomer resins, commercially availablefrom E. I. du Pont de Nemours and Company, and Iotek® ionomers,commercially available from ExxonMobil Chemical Company.

Silicone materials are also well suited for blending with compositionsdisclosed herein. Suitable silicone materials include monomers,oligomers, prepolymers, and polymers, with or without adding reinforcingfiller. One type of silicone material that is suitable can incorporateat least 1 alkenyl group having at least 2 carbon atoms in theirmolecules. Examples of these alkenyl groups include, but are not limitedto, vinyl, allyl, butenyl, pentenyl, hexenyl, and decenyl. The alkenylfunctionality can be located at any location of the silicone structure,including one or both terminals of the structure. The remaining (i.e.,non-alkenyl) silicon-bonded organic groups in this component areindependently selected from hydrocarbon or halogenated hydrocarbongroups that contain no aliphatic unsaturation. Non-limiting examples ofthese include: alkyl groups, such as methyl, ethyl, propyl, butyl,pentyl, and hexyl; cycloalkyl groups, such as cyclohexyl andcycloheptyl; aryl groups, such as phenyl, tolyl, and xylyl; aralkylgroups, such as benzyl and phenethyl; and halogenated alkyl groups, suchas 3,3,3-trifluoropropyl and chloromethyl. Another type of suitablesilicone material is one having hydrocarbon groups that lack aliphaticunsaturation. Specific examples include: trimethylsiloxy-endblockeddimethylsiloxane-methylhexenylsiloxane copolymers;dimethylhexenylsiloxy-endblocked dimethylsiloxane-methylhexenylsiloxanecopolymers; trimethylsiloxy-endblockeddimethylsiloxane-methylvinylsiloxane copolymers;trimethylsiloxyl-endblockedmethylphenylsiloxane-dimethylsiloxane-methylvinysiloxane copolymers;dimethylvinylsiloxy-endblocked dimethylpolysiloxanes;dimethylvinylsiloxy-endblocked dimethylsiloxane-methylvinylsiloxanecopolymers; dimethylvinylsiloxy-endblocked methylphenylpolysiloxanes;dimethylvinylsiloxy-endblockedmethylphenylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers;and the copolymers listed above wherein at least one group isdimethylhydroxysiloxy. Examples of commercially available siliconessuitable for blending with compositions disclosed herein includeSilastic® silicone rubber, commercially available from Dow CorningCorporation of Midland, Mich.; Blensil® silicone rubber, commerciallyavailable from General Electric Company of Waterford, N.Y.; andElastosil® silicones, commercially available from Wacker Chemie AG ofGermany.

Other types of copolymers can also be added to the golf ballcompositions disclosed herein. For example, suitable copolymerscomprising epoxy monomers include styrene-butadiene-styrene blockcopolymers in which the polybutadiene block contains an epoxy group, andstyrene-isoprene-styrene block copolymers in which the polyisopreneblock contains epoxy. Examples of commercially available epoxyfunctionalized copolymers include ESBS A1005, ESBS A1010, ESBS A1020,ESBS AT018, and ESBS AT019 epoxidized styrene-butadiene-styrene blockcopolymers, commercially available from Daicel Chemical Industries, Ltd.of Japan.

Ionomeric compositions used to form golf ball layers of the presentinvention can be blended with non-ionic thermoplastic resins,particularly to manipulate product properties. Examples of suitablenon-ionic thermoplastic resins include, but are not limited to,polyurethane, poly-ether-ester, poly-amide-ether, polyether-urea, Pebax®thermoplastic polyether block amides commercially available from ArkemaInc., styrene-butadiene-styrene block copolymers,styrene(ethylene-butylene)-styrene block copolymers, polyamides,polyesters, polyolefins (e.g., polyethylene, polypropylene,ethylene-propylene copolymers, ethylene-(meth)acrylate,ethylene-(meth)acrylic acid, functionalized polymers with maleicanhydride grafting, epoxidation, etc., elastomers (e.g., EPDM,metallocene-catalyzed polyethylene) and ground powders of the thermosetelastomers.

Also suitable for forming the center and outer core layers are thecompositions having high COR when formed into solid spheres disclosed inU.S. Patent Application Publication No. 2003/0130434 and U.S. Pat. No.6,653,382, the entire disclosures of which are hereby incorporatedherein by reference. Reference is also made to U.S. Patent ApplicationPublication No. 2003/0144087 for various ball constructions andmaterials that can be used in golf ball core, intermediate, and coverlayers.

Additional materials suitable for forming the core layers include thecore compositions disclosed in U.S. Pat. No. 7,300,364, the entiredisclosure of which is hereby incorporated herein by reference. Forexample, suitable center and outer core materials include HNPsneutralized with organic fatty acids and salts thereof, metal cations,or a combination of both. In addition to HNPs neutralized with organicfatty acids and salts thereof, core compositions may comprise at leastone rubber material having a resilience index of at least about 40.Preferably the resilience index is at least about 50. Polymers thatproduce resilient golf balls and, therefore, are suitable for thepresent invention, include but are not limited to CB23, CB22,commercially available from of Bayer Corp. of Orange, Tex., BR60,commercially available from Enichem of Italy, and 1207G, commerciallyavailable from Goodyear Corp. of Akron, Ohio. Additionally, theunvulcanized rubber, such as polybutadiene, in golf balls preparedaccording to the invention typically has a Mooney viscosity of betweenabout 40 and about 80, more preferably, between about 45 and about 65,and most preferably, between about 45 and about 55. Mooney viscosity istypically measured according to ASTM-D1646.

In addition to the above materials, the center can be formed from a lowdeformation material selected from metal, rigid plastics, polymersreinforced with high strength organic or inorganic fillers or fibers,and blends and composites thereof. Suitable low deformation materialsalso include those disclosed in U.S. Patent Application Publication No.2005/0250600, the entire disclosure of which is hereby incorporatedherein by reference.

EXAMPLES

It should be understood that the examples below are for illustrativepurposes only. In no manner is the present invention limited to thespecific disclosures herein.

Additional Examples of Suitable HNPs

The HNPs of Table 1 below have been found to be particularly useful asthe low modulus HNP and/or the high modulus HNP of the presentinvention.

TABLE 1 Flexural Hardness**, Hardness**, cation Modulus*, Shore C ShoreD Example source psi (18 day) (annealed) 1 Ca/Mg 71,600 88 57 2 Ca/Li70,300 89 58 3 Ca 70,100 92 60 4 Ca/Zn 60,400 88 58 5 Mg 38,300 84 52 6Mg 27,600 84 52 7 Mg 16,300 78 45 8 Mg 10,600 70 40 9 Mg 10,400 69 39*Flexural modulus was measured according to ASTM D790-03 Procedure B.**Hardness was measured according to ASTM D2240.

In embodiments of the present invention directed to a golf ball havingcenter formed from a low modulus HNP composition, Examples 6-9 areparticularly suitable for use as the low modulus HNP composition.

In embodiments of the present invention directed to a golf ball havingan outer core layer formed from a low modulus HNP composition, Examples5-9 are particularly suitable for use as the low modulus HNPcomposition.

In embodiments of the present invention directed to a golf ball having acenter formed from a high modulus HNP composition, Examples 1-6 areparticularly suitable for use as the high modulus HNP composition.

In embodiments of the present invention directed to a golf ball havingan outer core layer formed from a high modulus HNP composition, Examples1-4 are particularly suitable for use as the high modulus HNPcomposition.

Additional Examples of Suitable Ionomeric Cover Layer Compositions

Twelve ionomeric inner cover layer compositions according to the presentinvention were prepared by melt blending Surlyn® 8150 and Fusabond® 572Din a twin screw extruder, at a temperature of at least 450° F. (230°C.). The relative amounts of each component used are indicated in Table2 below.

Flex bars of each blend composition were formed and evaluated forhardness according to ASTM D2240 following 10 days of aging at 50%relative humidity and 23° C. The results are reported in Table 2 below.

TABLE 2 Surlyn ® Fusabond ® Shore C 8150, 572D, Hardness Example wt % wt% at 10 Days 1 89 11 91.2 2 84 16 89.8 3 84 16 90.4 4 84 16 89.6 5 81 1988.9 6 80 20 89.1 7 78 22 88.1 8 76 24 87.6 9 76 24 87.2 10 73 27 86.611 71 29 86.7 12 67 33 84.0

When numerical lower limits and numerical upper limits are set forthherein, it is contemplated that any combination of these values may beused.

All patents, publications, test procedures, and other references citedherein, including priority documents, are fully incorporated byreference to the extent such disclosure is not inconsistent with thisinvention and for all jurisdictions in which such incorporation ispermitted.

While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by those ofordinary skill in the art without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the examples and descriptions setforth herein, but rather that the claims be construed as encompassingall of the features of patentable novelty which reside in the presentinvention, including all features which would be treated as equivalentsthereof by those of ordinary skill in the art to which the inventionpertains.

1. A golf ball comprising a core and a cover, wherein the core has anoverall diameter of from 1.40 inches to 1.60 inches and consists of: (a)a center having a diameter of from 0.50 inches to 1.50 inches, a surfacehardness of 65 Shore C or greater, and a center hardness (H); (b) anintermediate core layer having a surface hardness (I) of 40 Shore C orgreater and formed from a high modulus HNP composition, the high modulusHNP composition comprising a highly neutralized ethylene/(meth)acrylicacid copolymer having a modulus of from 25,000 psi to 150,000 psi; and(c) an outer core layer having a surface hardness (S) of from 20 Shore Cto 70 Shore C and formed from a low modulus HNP composition, the lowmodulus HNP composition comprising a highly neutralizedethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer having amodulus of from 1,000 psi to 50,000 psi; wherein H<I and S<I, andwherein the modulus of the highly neutralized copolymer of the lowmodulus HNP composition is at least 10% less than the modulus of thehighly neutralized copolymer of the high modulus HNP composition.
 2. Thegolf ball of claim 1, wherein H<S, and wherein S−H=D, where D is aninteger from 1 to
 22. 3. The golf ball of claim 1, wherein S<H, andwherein H−S=D, where D is an integer from 1 to
 22. 4. The golf ball ofclaim 1, wherein the center has a diameter of from 0.750 inches to 1.500inches and the center hardness (H) is from 50 Shore C to 60 Shore C; theintermediate core layer surface hardness (I) is from 80 Shore C to 90Shore C; and the outer core layer has a thickness of from 0.010 inchesto 0.150 inches and the outer core layer surface hardness (S) is from 50Shore C to 60 Shore C.
 5. The golf ball of claim 4, wherein the outercore layer has a thickness of from 0.030 inches to 0.070 inches.
 6. Agolf ball comprising a core and a cover, wherein the core has an overalldiameter of from 1.40 inches to 1.60 inches and consists of: (a) acenter having a diameter of from 0.50 inches to 1.50 inches, a surfacehardness of 65 Shore C or greater, a center hardness (H), and formedfrom a low modulus HNP composition, the low modulus HNP compositioncomprising a highly neutralized ethylene/(meth)acrylic acid/alkyl(meth)acrylate copolymer having a modulus of from 1,000 psi to 50,000psi; (b) an intermediate core layer having a surface hardness (I) of 40Shore C or greater and formed from a high modulus HNP composition, thehigh modulus HNP composition comprising a highly neutralizedethylene/(meth)acrylic acid copolymer having a modulus of from 25,000psi to 150,000 psi; and (c) an outer core layer having a surfacehardness (S) of from 20 Shore C to 70 Shore C; wherein H<I and S<I, andwherein the modulus of the highly neutralized copolymer of the lowmodulus HNP composition is at least 10% less than the modulus of thehighly neutralized copolymer of the high modulus HNP composition.
 7. Thegolf ball of claim 6, wherein H<S, and wherein S−H=D, where D is aninteger from 1 to
 22. 8. The golf ball of claim 6, wherein S<H, andwherein H−S=D, where D is an integer from 1 to
 22. 9. The golf ball ofclaim 6, wherein the center has a diameter of from 0.750 inches to 1.500inches and the center hardness (H) is from 50 Shore C to 60 Shore C; theintermediate core layer surface hardness (I) is from 80 Shore C to 90Shore C; and the outer core layer has a thickness of from 0.010 inchesto 0.150 inches and the outer core layer surface hardness (S) is from 50Shore C to 60 Shore C.
 10. The golf ball of claim 9, wherein the outercore layer has a thickness of from 0.030 inches to 0.070 inches.
 11. Agolf ball comprising a core and a cover, wherein the core has an overalldiameter of from 1.40 inches to 1.60 inches and consists of: (a) acenter having a diameter of from 0.50 inches to 1.50 inches, a surfacehardness of 65 Shore C or greater, a center hardness (H), and formedfrom a low modulus HNP composition, the low modulus HNP compositioncomprising a highly neutralized ethylene/(meth)acrylic acid/alkyl(meth)acrylate copolymer having a modulus of from 1,000 psi to 50,000psi; (b) an intermediate core layer having a surface hardness (I) of 40Shore C or greater; and (c) an outer core layer having a surfacehardness (S) of from 20 Shore C to 70 Shore C and formed from a highmodulus HNP composition, the high modulus HNP composition comprising ahighly neutralized ethylene/(meth)acrylic acid copolymer having amodulus of from 25,000 psi to 150,000 psi; wherein H<I and S<I, andwherein the modulus of the highly neutralized copolymer of the lowmodulus HNP composition is at least 10% less than the modulus of thehighly neutralized copolymer of the high modulus HNP composition. 12.The golf ball of claim 11, wherein H<S, and wherein S−H=D, where D is aninteger from 1 to
 22. 13. The golf ball of claim 11, wherein S<H, andwherein H−S=D, where D is an integer from 1 to
 22. 14. The golf ball ofclaim 11, wherein the center has a diameter of from 0.750 inches to1.500 inches and the center hardness (H) is from 50 Shore C to 60 ShoreC; the intermediate core layer surface hardness (I) is from 80 Shore Cto 90 Shore C; and the outer core layer has a thickness of from 0.010inches to 0.150 inches and the outer core layer surface hardness (S) isfrom 50 Shore C to 60 Shore C.
 15. The golf ball of claim 14, whereinthe outer core layer has a thickness of from 0.030 inches to 0.070inches.
 16. A golf ball comprising a core and a cover, wherein the corehas an overall diameter of from 1.40 inches to 1.60 inches and consistsof: (a) a center having a diameter of from 0.50 inches to 1.50 inches, asurface hardness of 65 Shore C or greater, a center hardness (H), andformed from a high modulus HNP composition, the high modulus HNPcomposition comprising a highly neutralized ethylene/(meth)acrylic acidcopolymer having a modulus of from 25,000 psi to 150,000 psi; (b) anintermediate core layer having a surface hardness (I) of 40 Shore C orgreater; and (c) an outer core layer having a surface hardness (S) offrom 20 Shore C to 70 Shore C and formed from a low modulus HNPcomposition, the low modulus HNP composition comprising a highlyneutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymerhaving a modulus of from 1,000 psi to 50,000 psi; wherein H<I and S<I,and wherein the modulus of the highly neutralized copolymer of the lowmodulus HNP composition is at least 10% less than the modulus of thehighly neutralized copolymer of the high modulus HNP composition. 17.The golf ball of claim 16, wherein H<S, and wherein S−H=D, where D is aninteger from 1 to
 22. 18. The golf ball of claim 16, wherein S<H, andwherein H−S=D, where D is an integer from 1 to
 22. 19. The golf ball ofclaim 16, wherein the center has a diameter of from 0.750 inches to1.500 inches and the center hardness (H) is from 50 Shore C to 60 ShoreC; the intermediate core layer surface hardness (I) is from 80 Shore Cto 90 Shore C; and the outer core layer has a thickness of from 0.010inches to 0.150 inches and the outer core layer surface hardness (S) isfrom 50 Shore C to 60 Shore C.
 20. The golf ball of claim 19, whereinthe outer core layer has a thickness of from 0.030 inches to 0.070inches.